know why over 80% of all arrests for motor vehicle theft fail to end in conviction, and why about 60% of all arrests for robbery and burglary fail as well.

On one hand, since the data collection in SCPS begins at filing, all of the decisions made prior to filing are lost. On the other hand, many important decisions made after filing are captured in this data collection. For those cases filed, it is possible to assess the amount of charge mobility that occurs from arrest to filing, through adjudication and sentencing. There is also extensive information on pretrial custody decisions and status, time that it takes to complete stages of processing, as well as some criminal history data.

The key limitation of the NPS in understanding trends in prosecution is that it is to prosecution what the LEMAS survey is to law enforcement: a strictly partial look at basic administrative and management information. As an establishment survey, it has the same potential respondent selection problems (effects) as other surveys; there is also a certain inherent amount of noncomparability across prosecutorial units, because one can serve a single county and another an entire state. For what information it does provide on the dynamics of personnel and workload in prosecutor’s offices, the NPS has suffered as a measurement device because of its unstable periodicity (shifting from a 2-year to a 5-year cycle). It has also been unstable in the degree to which it has been conducted and treated as a sample or a census, as we described in Section 3–D; in the “census” years, content is particularly pared back, excluding all but the basic administrative questions.

The Federal Justice Statistics Program operated by the Urban Institute with BJS sponsorship links administrative records across decision point in the federal justice system. It does provide the “flow” data that the “funnel” promises, and it does cover more of the decisions made by prosecutors than the SCPS series (including the declination decision). However, it is strictly limited to the federal justice system.

There are senses in which prosecution and prosecutorial decisions should be amenable to data collection efforts, among them the fact that basic concepts and definitions are relatively invariant. In broad strokes, Forst (2000:22) observes that changes in prosecution “have mostly followed rather than led developments outside the prosecution domain. The basic nature and goals of prosecution, the role of the victim as witness in a matter between the state and defendant, the essential steps in processing cases through the courts and systems of public accountability have all remained fundamentally unchanged over the past 30 years.” However, a major reason for this resistance to procedural change—the relative insularity of prosecutors, as opposed to the police and elected officials whose work has a larger